The present invention is directed, in general, to subterranean exploration and production and, more specifically, to a system and method for placing multiple sensors in a subterranean well and obtaining subterranean parameters from the sensors.
The oil industry today relies on many technologies in its quest for the location of new reserves and to optimize oil and gas production from individual wells. Perhaps the most general of these technologies is a knowledge of the geology of a region of interest. The geologist uses a collection of tools to estimate whether a region may have the potential for holding subterranean accumulations of hydrocarbons. Many of these tools are employed at the surface to predict what situations may be present in the subsurface. The more detailed knowledge of the formation that is available to the geophysicist, the better decisions that can be made regarding production.
Preliminary geologic information about the subterranean structure of a potential well site may be obtained through seismic prospecting. An acoustic energy source is applied at the surface above a region to be explored. As the energy wavefront propagates downward, it is partially reflected by each subterranean layer and collected by a surface sensor array, thereby producing a time dependent recording. This recording is then analyzed to develop an estimation of the subsurface situation. A geophysicist then studies these geophysical maps to identify significant events that may determine viable prospecting areas for drilling a well.
Once a well has been sunk, more information about the well can be obtained through examination of the drill bit cuttings returned to the surface (mud logging) and the use of open hole logging techniques, for example: resistivity logging and parameter logging. These methods measure the geologic formation characteristics pertaining to the possible presence of profitable, producible formation fluids before the well bore is cased. However, the reliability of the data obtained from these methods may be impacted by mud filtration. Additionally, formation core samples may be obtained that allow further, more direct verification of hydrocarbon presence.
Once the well is cased and in production, well production parameters afford additional data that define the possible yield of the reservoir. Successful delineation of the reservoir may lead to the drilling of additional wells to successfully produce as much of the in situ hydrocarbon as possible. Additionally, the production of individual zones of a multi-zone well may be adjusted for maximum over-all production.
Properly managing the production of a given well is important in obtaining optimum long-term production. Although a given well may be capable of a greater initial flow rate, that same higher initial production may be counter to the goal of maximum overall production. High flow rates may cause structural changes to the producing formation that prevents recovering the maximum amount of resident hydrocarbon. In order to optimize production of a given well, it is highly desirable to know as much as possible about the well, the production zones, and surrounding strata in terms of temperature, pressure, flow rate, etc. However, direct readings are available only within the confines of the well and produce a two-dimensional view of the formation.
As hydrocarbons are depleted from the reservoir, reductions in the subsurface pressures typically occur causing hydrocarbon production to decline. Other, less desirable effects may also occur. On-going knowledge of the well parameters during production significantly aids in management of the well. At this stage of development, well workover, as well as secondary and even tertiary recovery methods, may be employed in an attempt to recover more of the hydrocarbon than can be produced otherwise. The success of these methods may only be determined by production increases. However, if the additional recovery methods either fail or meet with only marginal success, the true nature of the subsurface situation may typically only be postulated. The inability to effectively and efficiently measure parameters in existing wells and reservoirs that will allow the determination of a subterranean environment may lead to the abandonment of a well, or even a reservoir, prematurely.
One approach to obtaining ongoing well parameters in the well bore has been to connect a series of sensors to an umbilical, to attach the sensors and umbilical to the exterior of the well casing, and to lower the well casing and sensors into the well. Unfortunately, in the rough environment of oil field operation, it is highly likely that the sensors or the umbilical may be damaged during installation, thus jeopardizing data acquisition.
Accordingly, what is needed in the art is a multi-parameter sensing system that: (a) overcomes the damage-prone shortcomings of the umbilical system, (b) may be readily placed in a well bore, as deep into the geologic formation as possible, (c) can provide a quasi three-dimensional picture of the well, and (d) can be interrogated upon command.
To address the above-discussed deficiencies of the prior art, the present invention provides a self-contained sensor module for s use in a subterranean well that has a well transmitter or a well receiver associated therewith. In one embodiment, the sensor module comprises a housing, a signal receiver, a parameter sensor, an electronic control assembly, and a parameter transmitter. The receiver, sensor, control assembly and transmitter are all contained within the housing. The housing has a size that allows the module to be positioned within a formation about the well or in an annulus between a casing positioned within the well and an outer diameter of the well. The signal receiver is configured to receive a signal from the well transmitter, while the parameter sensor is configured to sense a physical parameter of an environment surrounding the sensor module within the well. The electronic control assembly is coupled to both the signal receiver and the parameter sensor, and is configured to convert the physical parameter to a data signal. The parameter transmitter is coupled to the electronic control assembly and is configured to transmit the data signal to the well receiver.
In an alternative embodiment, the sensor module further includes an energy storage device coupled to the signal receiver and the electronic control assembly. The energy storage device may be various types of power sources, such as a battery, a capacitor, or a nuclear fuel cell. In another embodiment, the sensor module also includes an energy converter that is coupled to the signal receiver. The energy converter converts the signal to electrical energy for storage in the energy storage device. In yet another embodiment, the signal receiver may be an acoustic vibration sensor, a piezoelectric element or a triaxial voice coil.
In a preferred embodiment, the sensor module has a size that is less than an inner diameter of an annular bottom plug in the casing. In this embodiment, there is an axial aperture through the annular bottom plug and a rupturable membrane disposed across the axial aperture.
In another embodiment, the signal receiver and the parameter transmitter are a transceiver. The physical parameter to be measured may be: temperature, pressure, acceleration, resistivity, porosity, or flow rate. In advantageous embodiments, the signal may be electromagnetic, seismic, or acoustic in nature. The housing may also be a variety of shapes, such as prolate, spherical, or oblate spherical. The housing, in one embodiment, may be constructed of a semicompliant material.
The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.